This invention relates to a device for introducing an article into and withdrawing the same from the interior of a chamber sealed from the surrounding environment. More particularly, the invention relates to a test bar movably supported in a gastight manner in a housing coupled with a vacuum chamber. The test bar is adapted to support a sample, for example, in a recess, and has a length so dimensioned that the bar, whether the recess is internally or externally of the chamber, performs its function regarding the sealing of the chamber with respect to its environment.
It is a common characteristic of a great number of manufacturing or testing methods involving vacuumized environment that the articles, substances, substrates or specimens (hereinafter simply referred to as "specimen") have to be brought into a closed vacuum vessel from the ambient, atmospheric environment. In the simplest case, the vacuum device is de-vacuumized, opened and the specimens are introduced. Thereafter the device is again closed and evacuated. Particularly when the specimen is to be exposed to high vacuum or ultra high vacuum, the above-outlined mode of introducing the specimen inherently involves significant loss of time. For this purpose, various types of vacuum locks have been designed.
The locks in general comprise a vacuumizable pre-chamber which is closed by two sealing systems or valves. This pre-chamber is coupled through one sealing system or valve with the principal vacuum chamber and through a further sealing system or valve with the atmospheric air. The specimen is first brought from the atmosphere into the pre-chamber. Thereafter the pre-chamber is vacuumized, whereupon the specimen is moved into the principal vacuum chamber. According to a particularly advantageous known solution of a vacuum lock, the specimen is positioned in a recess of an otherwise linear, smooth and polished cylindrical bar. The bar which serves for transporting the specimen from the atmospheric outer environment into the principal vacuum chamber is guided in a housing coupled to the vacuum chamber. In the housing, there are provided O-rings or O-ring systems surrounding the rod for providing a packing system for sealing the chamber from the surrounding environment. Since the bar should perform its sealing function in any geometric position of the specimen, the bar has to extend on either side of the specimen to such a distance that the bar, in any position, fully cooperates with the O-ring system. Instead of O-rings, other sealing arrangements may be used, such as magneto-fluid or labyrinth seal. It is a disadvantage of this arrangement that in case the test bar is to be replaced, the entire vacuum system has to be de-vacuumized if no additional valve is provided. Such a replacement is necessary, for example, if a specimen or several specimens are to be handled under different conditions. Thus, different test bars are used for different temperature ranges (for example, for ranges of -180.degree. to +350.degree. C, 20.degree. to 600.degree. C and 20.degree. to 1500.degree. C) and for different specimen configurations.